2 Energy in the Atmosphere Radiation: Energy Transfer by Waves: The Earth receives energy from the sun by radiation. Radiation is the transfer of energy as electromagnetic waves.Conduction: Energy Transfer by Contact: Thermal conduction is the transfer of thermal energy by direct contact through a material.Convection: Energy Transfer by Circulation Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas (fluids) by convection currents.
5 The Greenhouse EffectThe Greenhouse Effect and Life on Earth: The greenhouse effect is the process by which gases in the atmosphere absorb thermal energy and radiate it back to Earth.
6 GreenhouseGreenhouses allow light to pass through the glass. This light strikes the plants and materials inside the greenhouse and is turned into heat.Heat cannot pass back through the glass, so it gets warmer inside the greenhouse.You see the same thing on a hot summer day when you leave the car windows rolled up!
7 Greenhouse Effect (a good thing!) Without the greenhouse effect life on this planet would probably not exist as the average temperature of the Earth would be a chilly -18° Celsius, rather than the present 15° Celsius.
8 Greenhouse Gases water vapor: occurs naturally in the atmosphere. carbon dioxide: produced naturally when people and animals breathe. Plants and trees absorb carbon dioxide to live. Volcanoes also produce this gas.methane: comes from animals as they digest their food.ozone: occurs naturally in the atmosphere.
9 Enhanced Greenhouse Effect Activities of man also produce greenhouse gases. These gases keep increasing in the atmosphere. The balance of the greenhouse gases changes and this could have effects on the whole planet.Burning fossil fuels - coal, oil and natural gas - releases carbon dioxide into the atmosphere. Cutting down and burning trees also produces a lot of carbon dioxide.
10 Human Caused Global Warming If more and more greenhouse gases are in the atmosphere, more heat is trapped which makes the Earth warmer. This is called global warming.Some scientists think that man's activities are increasing the natural greenhouse effect.This could have dangerous effects on the Earth.Your job as citizens is to find out the truth, is global warming a natural cycle or human induced. Learn all the science you can, and make an informed decision!
11 Effects Summers and winters would be warmer. Some places would be wetter or drier, affecting farming.Sea levels would rise as the ice caps melt.Life on the planet would have to adapt to these changes.
12 The DebateOver the last 4 billion years, climates on the Earth have constantly changed.As we are coming out of an ice age, is this warming trend natural or man- made.The debate continues!
15 Radiation BalanceThe Radiation Balance: Energy In, Energy Out The amount of energy Earth receives and the amount of energy returned to space must be approximately equal.
16 Why Air MovesAir Rises at the Equator and Sinks at the Poles As the cold, more dense air sinks, it creates areas of high pressure around the poles. This cold polar air then flows toward the equator, where the warm air creates low pressure.Pressure always goes from high to low. The high pressure air wants to fill in the low pressure area.Pressure Belts Are Found Every 30º Convection cells are separated by pressure belts, bands of high and low pressure.
20 Pressure always fills in from high to low! Local WindsLocal winds generally move short distances and can blow from any direction.Mountain and valley breezes are examples of local winds caused by an area’s geography.Sea and land breezes are affected by temperature.Pressure always fills in from high to low!
22 The Ozone HoleThe Earth’s protective ozone layer is thinning over the Arctic and Antarctic regions. These ozone holes allow more UV radiation, which damages genes and can cause skin cancer, to reach the earth’s surface.Cooperation to Reduce the Ozone Hole In 1987, many nations agreed to reduce the use of CFCs, the chemicals that cause ozone depletion. Because CFCs remain active for 60 to 120 years, however, it will take many years for the ozone layer to recover.
23 Chapter 15 Ozone and Ozone Holes Section 4 Air Pollution Click below to watch the Visual Concept.Visual Concept